Diverter cover assembly and methods of use

ABSTRACT

A diverter cover assembly includes a first arrangement of sliding plates positioned above a central bore of a diverter and movable in substantially opposite directions to open and close over the central bore.

BACKGROUND

1. Field of the Disclosure

Embodiments disclosed herein relate generally to subsea drilling More particularly, embodiments disclosed herein relate to a diverter cover assembly and methods of using the diverter cover assembly.

2. Background Art

Wellbores are drilled deep into the earth's crust to recover oil and gas deposits trapped in the formations therein. Typically, these wellbores are drilled using a drill bit rotated on an end of a drillstring. Because of the energy and friction involved in drilling a wellbore in the earth's formation, drilling fluids, commonly referred to as drilling mud, are used to lubricate and cool the drill bit as it cuts through the rock formations. Furthermore, in addition to cooling and lubricating the drill bit, drilling mud also performs the secondary function of removing the drill cuttings from the bottom of the wellbore and applying a hydrostatic column of pressure to the drilled wellbore.

Referring to FIG. 1A, a portion of a drilling platform 5 is shown. Drilling platform 5 includes a rig floor 10 and a lower bay 15. A riser assembly 20 extends from a subsea wellhead (not shown) to the drilling platform 5 and includes various fluid control components. One fluid control component is a diverter 50, which is connected to the upper end of the riser assembly 20. A larger view of the diverter 50 is shown in FIG. 1B. The diverter 50 has a central bore 52 and fluid ports 54 which allow drilling mud returning up through the riser assembly 20 (FIG. 1A) to flow to a mud pit area for cleaning and recirculation.

Oftentimes, tools and equipment are accidentally dropped down an annulus (not shown) or the central bore 52 of the diverter 50 while performing maintenance, which requires running retrieval equipment or tools downhole and retrieving these items before continuing operation. Previously, to cover the central bore 52 of the diverter 50, a cover of some type, such as a wooden board, was pulled across the central bore 52 when performing maintenance to prevent tools from falling downhole. However, any type of drillpipe running through the diverter 50 rendered this method ineffective.

Accordingly, there exists a need for a diverter cover assembly that prevents costly and time consuming retrieval of dropped tools from a wellbore and that is capable of closing on variable diameter pipe as well as open holes.

SUMMARY OF THE DISCLOSURE

In one aspect, embodiments disclosed herein relate to a diverter cover assembly including a first arrangement of sliding plates positioned above a central bore of a diverter and movable in substantially opposite directions to open and close over the central bore.

In other aspects, embodiments disclosed herein relate to a method of using a diverter cover assembly including providing a diverter cover assembly having a first arrangement of sliding plates positioned above a central bore of a diverter and movable in substantially opposite directions and moving the first arrangement of sliding plates and closing the central bore of the diverter.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A shows a schematic view of a drilling rig and riser assembly.

FIG. 1B shows a perspective view of a diverter.

FIG. 2A shows a perspective view of a diverter cover assembly in accordance with one or more embodiments of the present disclosure.

FIG. 2B shows a perspective view of an adaptor plate on a diverter in accordance with one or more embodiments of the present disclosure.

FIG. 3A shows a side view of multiple sliding plates of a diverter cover assembly in accordance with one or more embodiments of the present disclosure.

FIG. 3B shows a perspective view of the diverter cover assembly of FIG. 3A.

FIG. 4A shows a top view of a diverter cover assembly in a fully open position in accordance with one or more embodiments of the present disclosure.

FIG. 4B shows a top view of a diverter cover assembly in a fully closed position in accordance with one or more embodiments of the present disclosure.

FIGS. 5A-5C show top views of a diverter cover assembly closed around variable pipe sizes in accordance with one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

The following description is directed to various exemplary embodiments of the disclosure. The embodiments disclosed herein should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, those having ordinary skill in the art will appreciate that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

In one aspect, embodiments disclosed herein relate to a wellbore cover assembly that prevents tools and/or other equipment from being dropped into a wellbore. Particularly, certain embodiments of the present disclosure may relate to a diverter cover assembly that is coupled or attached on top of a diverter assembly and prevents dropping tools and equipment down an annulus or bore of the diverter during maintenance. The diverter cover assembly may be closed around variable pipe diameters, or may be closed over an open hole absent any pipe running through the diverter.

Referring now to FIG. 2A, a perspective view of a diverter cover assembly 100 in accordance with one or more embodiments of the present disclosure is shown. The diverter cover assembly 100 includes an outside sliding plate 122 and an inside sliding plate 124 which are movable in opposite directions to open and close over a central bore 52 of the diverter 50. The outside sliding plate 122 is movable with hydraulic cylinders 130, and extendable pistons (not shown) of the hydraulic cylinders 130 are connected to the outside sliding plate 122 by pins 127 or other similar linkages. For example, the hydraulic piston may have a rod clevis or other attachment device on an end thereof for attachment to the sliding plate 122.

Similarly, the inside sliding plate 124 is operable with hydraulic cylinders 132, and extendable pistons (not shown) of the hydraulic cylinders 132 are connected to the inside sliding plate 124 by pins (not shown) or other similar linkages. The outside sliding plate 122 and inside sliding plate 124 may be positioned at slightly different heights above the diverter 50 so that in a closed position the sliding plates may slightly overlap to completely close over the central bore 52 of the diverter. Either the outside sliding plate 122 may pass over the inside sliding plate 124, or vice versa. In certain embodiments, there may be a vertical clearance between the outside sliding plate 122 and the inside sliding plate 124 (as the outside sliding plate 122 passes over or under the inside sliding plate 124). Example vertical clearances include clearances of about one quarter inch, one-half inch, and one inch. In other embodiments, the vertical clearance may be greater than one inch.

A separate hydraulic system (not shown) may provide hydraulic pressure to operate the hydraulic cylinders. In certain embodiments, the hydraulic cylinders may be operated at around 3,000 psi. This may be beneficial because of the hydraulic supply provided on a drilling rig, which may typically have a hydraulic system pressure of around 3,000 psi. In other embodiments, the hydraulic cylinders may be operated within a range of about 1,500 and 5,000 psi.

The outside sliding plate 122 and inside sliding plate 124 are movable back and forth over the central bore 52 of the diverter 50 (in opposite directions) by extending and retracting pistons of the hydraulic cylinders 130 and 132, respectively. In certain embodiments, the hydraulic cylinders 130 and 132 may be 1½ inch bore size hydraulic cylinders; however, those skilled in the art will appreciate other hydraulic cylinders sizes that may be used, both larger and smaller In alternate embodiments, one of ordinary skill in the art will understand that pneumatic cylinders or electric motors may also be used to move the sliding plates. In some embodiments, a controller or control system (e.g., a computer or other electronic device) may interface with components used to move the sliding plates (e.g., hydraulic, electric, pneumatic cylinders), such that an operator may provide inputs to effect movement of the sliding plates.

The outside sliding plate 122 is a crescent-shaped plate having a substantially circular inner diameter 123. It will be understood that the outside sliding plate 122 may be formed in other shapes or configurations as well. Similarly, the inside sliding plate 124 may be a crescent-shaped plate or otherwise. The inside sliding plate 124 has a substantially circular inner diameter 125, which when brought together with the circular inner diameter 123 of outside sliding plate 122, forms a substantially circular diameter that may be closed around variable diameters of drillstring. The sliding plates 122 and 124 may generally be relatively thin metal plates which are cut to shape using a saw or torch, or other known cutting methods. Other rigid materials may also be used for the sliding plates 122 and 124. For example, in certain embodiments, the plates 122 and 124 may have a thickness of between about 1 and 5 inches. Alternatively, the sliding plates 122 and 124 may be thicker plates depending on the amount of strength desired to resist or support equipment that may be accidentally dropped thereon.

Referring briefly to FIG. 2B, in certain embodiments, an adaptor plate 60 may be fastened on top of the diverter 50. The adaptor plate 60 may provide a mount or structure on which the diverter cover assembly 100 may be installed onto the top of the diverter 50. Additionally, the adaptor plate 60 may provide mounting locations for other components, including, but not limited to, a control block (not shown) or other hydraulic equipment. In addition, the adaptor plate 60 may include drainage slots (not shown) for drainage of fluids from the wellbore. The adaptor plate 60 may be attached to the diverter 50 by one or more bolts 62 or other threaded fasteners, or other methods of attachment known to one of ordinary skill in the art. For example, in certain embodiments, the adaptor plate 60 is attached to the top of diverter 50 with four 1-½ inch bolts. Further, the adaptor plate 60 may be configured in two halves, which may be split in half for quick emergency removal of the diverter cover assembly 100 from the diverter 50. Those skilled in the art will appreciate other adaptor plates or cover plates that may be used to facilitate attachment of the diverter cover assembly to various types of diverters having various configurations, bolt circle patterns, or other configurations requiring an adaptor.

Now referring to FIGS. 3A and 3B, a diverter cover assembly 100 having multiple sets or arrangements of sliding plates in accordance with one or more embodiments of the present disclosure is shown. For example, an upper arrangement of sliding plates 110 may be coupled or attached (similar to attachment of the lower sliding plates 120) above a lower arrangement of sliding plates 120 as shown in FIGS. 3A and 3B. Additional arrangements of sliding plates (such as upper sliding plates 110) include the same components and operate the same as that described for the first arrangement of sliding plates 120 above. In certain embodiments, there may be a vertical clearance of about 1-½ inches between the lower arrangement of sliding plates 120 and the upper arrangement of sliding plates 110. Both the upper arrangement of sliding plates 110 and the lower arrangement of sliding plates 120 are configured to open and close over the central bore of the diverter 50. Those skilled in the art will further understand that additional arrangements of sliding plates may be fastened above the two sets of sliding plates 110 and 120 shown in the figures. Each additional arrangement of sliding plates may include one or more additional hydraulic cylinders for operation (i.e., to move one or more sliding plates open or closed across the central bore of the diverter 50).

In certain embodiments, as shown in FIGS. 4A and 4B, the upper arrangement of sliding plates 110 and the lower arrangement of sliding plates 120 may be misaligned, that is, a sliding axis ‘A’ on which the upper arrangement of sliding plates 110 move (i.e., open and close) may be positioned differently from a sliding axis ‘B’ upon which the lower sliding plates 120 move. For example, in certain embodiments, the sliding axis A of the upper arrangement of sliding plates 110 may be rotated approximately 90 degrees from the sliding axis B of the lower arrangement of sliding plates 120. In other embodiments, the sliding axes of the upper and lower arrangements of sliding plates 110 and 120 may be rotated to be any other angle between approximately 0 degrees and 90 degrees. One of ordinary skill in the art will appreciate various angles of misalignment between the upper arrangement of sliding plates 110 and the lower arrangement of sliding plates 120.

Referring still to FIGS. 4A and 4B, top views of the diverter cover assembly 100 in open and closed positions in accordance with one or more embodiments of the present disclosure are shown. FIG. 4A illustrates the diverter cover assembly 100 in a fully opened position, in which hydraulic cylinders are retracted completely. FIG. 4B illustrates the diverter cover assembly 100 in a fully closed position, in which hydraulic cylinders are extended completely to close the diverter. Thus, the diverter cover assembly 100 is capable of completely closing over an open central bore of the diverter 50.

Further, as shown in FIGS. 5A-5C, top views of the diverter cover assembly 100 closed around various tubular diameters in accordance with one or more embodiments of the present disclosure are shown. The diverter cover assembly 100 is capable of closing around variable pipe and casing sizes as well as complete shut-off of a wellbore without drillpipe (i.e., the sliding plates overlap and completely close over the open wellbore).

Methods of using a diverter cover assembly 100 as described above are as follows, and in reference to FIGS. 1B-5C. The diverter cover assembly 100 is fastened to a top of the diverter 50, either directly, or using an adaptor plate 60. The diverter cover assembly 100 may be fastened to the diverter 50 or adaptor plate 60 using threaded fasteners or other known attachment methods. To close the sliding plate arrangements 110 and 120 of the diverter cover assembly 100, the hydraulic cylinders (or electric or pneumatic cylinders) may be actuated to cause the sliding plates to move toward each and close over the central bore of the diverter 50. If no drillpipe is present through the diverter 50, the sliding plates may completely overlap each other and completely close over the central bore 52 of the diverter 50 (as shown in FIG. 4B). In the event that drillpipe is present through the diverter 50, the sliding plates may close until they contact a diameter of the drillpipe (as shown in FIGS. 5A-5C), at which point the diverter 50 is completely closed.

The sliding plates may be moved and closed around any diameter of drillpipe extending through the diverter. For example, in certain embodiments, the diverter cover assembly 100 may include sensors (not shown) that indicate when the sliding plates make contact with the drillpipe, which automatically stops further closing of the sliding plates. In other embodiments, an operator may manually adjust the sliding plates until they contact the drillpipe. In still further embodiments, the sliding plates may be closed proximate the drillpipe while not in contact, such that only a small gap (e.g., ½ inch) exists between the closed sliding plates and the drillpipe to prevent any tools or other objects from falling into the wellbore. In other embodiments, the diverter cover assembly 100 and related control circuitry may be configured to detect obstructions between the sliding plates and the drillpipe (e.g., the hand of an operator) and open the sliding plates to prevent damage or injury.

Advantageously, embodiments of the present disclosure provide a diverter cover assembly that is capable of closing a diverter in any situation to perform maintenance without the worry of objects falling down the wellbore through an open diverter and disrupting activity. It may also prevent damage to the top of the diverter and inside the diverter. The diverter cover assembly may be easily retrofitted on existing diverters or installed on new diverters. In addition, the diverter cover assembly may be operated using hydraulic pressure already available on the drilling rig.

While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims. 

What is claimed is:
 1. A diverter cover assembly, comprising: a first arrangement of sliding plates positioned above a central bore of a diverter and movable in substantially opposite directions to open and close over the central bore.
 2. The diverter cover assembly of claim 1, further comprising a second arrangement of sliding plates positioned above the first arrangement of sliding plates and movable in substantially opposite directions to open and close over the central bore.
 3. The diverter cover assembly of claim 2, further comprising one or more hydraulic cylinders to move the first and second arrangements of sliding plates.
 4. The diverter cover assembly of claim 2, further comprising one or more pneumatic cylinders to move the first and second arrangements of sliding plates.
 5. The diverter cover assembly of claim 2, further comprising one or more electric motors to move the first and second arrangements of sliding plates.
 6. The diverter cover assembly of claim 2, wherein a sliding axis of the first arrangement of sliding plates is rotated relative to a sliding axis of the second arrangement of sliding plates.
 7. The diverter cover assembly of claim 1, further comprising an adaptor plate configured to be attached on top of the diverter and onto which the diverter cover assembly is fastened.
 8. The diverter cover assembly of claim 1, wherein the first arrangement of sliding plates is retrofitted on a diverter.
 9. A method of using a diverter cover assembly, the method comprising: providing a diverter cover assembly having a first arrangement of sliding plates positioned above a central bore of a diverter and movable in substantially opposite directions; and moving the first arrangement of sliding plates and closing the central bore of the diverter.
 10. The method of claim 9, further comprising providing a second arrangement of sliding plates positioned above the first arrangement of sliding plates.
 11. The method of claim 10, further comprising moving the first and second arrangements of sliding plates with hydraulic cylinders attached thereto.
 12. The method of claim 10, further comprising moving the first and second arrangements of sliding plates with pneumatic cylinders attached thereto.
 13. The method of claim 10, further comprising moving the first and second arrangements of sliding plates with electric motors attached thereto.
 14. The method of claim 10, wherein a sliding axis of the first arrangement of sliding plates is rotated relative to a sliding axis of the second arrangement of sliding plates. 